Halve the squash lengthwise and score the flesh with a big, sharp knife, so that the heat is better distributed and it cooks more evenly. Place the two halves, orange side up, on a tray and add small knobs of butter on top. Season with salt and pepper, and put it in a hot oven for one hour, or until the squash is tender. I had fresh thyme handy, so I added the leaves of some twigs.